What about the offset?

Started to read a book called Motorcycle Dynamics, which dives into the physics of handling bike in quite a details. That brings me back to the Geometry -post where I mentioned the steering axle and fork main offset. Offset can be used to adjust the trail, but it has some other implications as well.

One thing offset does is that it reduces the up and down motion of the front when turning the handlebar. Since the steering is not in upright position the center of the front wheel lowers. The plot is an example of calculations with 32 degree caster angle (angle of steering axel from vertical line) and 32 cm wheel radius.

Calculations  assume still some silly stuff like dimensionless wheels and hence no roll at all. Plus I'm severely hangoverish from yesterdays party at the garage so I'm not promising anything of this is 100% correct

So what? Good question, I've no clue about what all that means. But at least pumping front up and down is not nice for handling since it makes it heavy. If there is 150kg of weight on front wheel you will be pulling that up and lowering down in every turn.

Random pics maybe related to something but probably not

Harry potterism of building bikes

There is something funny and fascinating about the whole culture of craftmanship around building bikes. First of all, there is no internet here. If I need to find someone to measure and bore the engine I will not find that person by googling it. They way these masters are found is by knowing someone, who knows someone who knows a person with a beard like Dumbledore and a skill of resurrecting engines that are know to be dead for decades.

These dumbledores can be found in addresses like seven and half of a street that probably is not on a map. After finding the building there will be about dozen iron doors with no signs of what so ever, so one needs to be good at guessing, have a guide or go knocking on all the doors until the right one is found. When the right one is found there will be someone speaking in dialect barely understandable to anyone who was not born on a bike - and he will be asking who sent you. If you answer that question right you may be granted access to dungeon of parts, tobacco smoke, machinery and bikes that are so hand made and customised I'm willing to believe they are constructed atom by atom.

So cool.

Pic not related but the whole blog looks so damn boring if there are no pics in the posts. This is from Norrtälje show in May 2015. Or was it June.

Visualizing the frame

That is about how it is going to be. Tape is a guide for an eye on how the frame is going to be. I'm not sure about the oil tank - it's funny but, well it's funny. And also it might turn out to be very impractical in shape and difficult to fit.

It's not going to be a chopper. Thing which sometimes seems to raise strong opinions.

There was a swap meet and afterparty some weeks ago where I tried to get to know and into discussions with different people who might be able to work with the engine and the transmission. Engine at least needs to be measured and most likely bored as I'm expecting little damaged. Anyway, as part of these discussions I got plenty of opinions what the bike should be. Especially there were couple of nice and very skilful chopper builders who really seemed to struggle with trying to comprehend why an earth someone would not build a chopper. They were all like "why build a bike at all if it's not going to be chopper". Good question, but building bikes makes no sense anyway - its extremely expensive way of getting possession of something highly impractical. Still not making a chopper, at least not from this one but the next time I just might.

And I did promise to pay these aforementioned chopper dudes a visit and maybe learn something more about what they do and how.

Cleaning up

The rims were found to be round enough to keep working with. So the next step was to get the beautiful assistant participating in contamination removal procedures.

Measuring roundness

I'm keeping the old rims for two reasons. The real reason is convenience and money - since they are there and they seem sort of decent why waste money for new ones. To everybody else I'm telling that I'm saving the precious change percents because it's much cooler reason than being cheap or just broke.

But how decent the rims actually are? I did very scientific measurement for roundness and the spatial displacement (see the pic). I put the wheel on solid stand where I can rotate it and then I have the cord with a bolt pendulum with a tape marker on it. This was actually pretty accurate, and it gets better with a hint of modern tech -- put the wheel spinning and take slow motion video with a phone. Gives easily accuracy less than millimeter.

They are round and flat with displacement less than the mentioned one millimeter.

Geometry

I know I said something about digging into the geometry of the frame and angles. I did some of it but never wrote about it. Mostly because I didn't bother to draw any pictures or do any real math - but here is some of the thinking I did.

Let's start with a pic that I took from the tool that knowledgeable people nearby have made.

There are three different measures that typically are discussed; First one is called trail and is the measure J in the pic. It is the distance between the point where imaginary continuation of steering axle hits the ground and the point where the tyre touches the ground.

Bearded wise men, much like Gandalf, can tell that about 10cm of trail is good. If the trail is less the steering becomes volatile and if it's too much the bike becomes heavy to handle. Heavy meaning that it's almost too stable at the middle but there may be a sudden kink at certain angle where steering collapses to a side. So, as many times is in life, too little is as bad and so is too much, but for different reason.

While we try to aim in getting the trail to close to the magical 10cm we have some freedom of choice. We have chosen the tyres already so those measures are fixed. But if we stretch the front we can adjust the height of the steering axel top from the ground. I'm not going to do that because I don't have to. If I was making a chopper then it would be inevitable. But we still have couple of things left we can adjust - the rake angle, which is the angle between the steering axle and fork and the offset of steering axel and fork neck.

The measures in the picture are somewhat close to what makes sense but not final for my bike. I will have to see the rake angle in its place when the rest of the frame is ready.

But the million dollar question I was pondering on was that why exactly in mathematical sense the trail needs to be something and what is the physics behind when it is wrong? There are two main reasons why bikes can be ridden at higher speeds to begin with. The explanation typically given in the driving schools, or at least given to me, is the precession - i.e. momentum related to rotating object and it's reluctancy to change it's position. Fine, I buy that and it is part of the reason but not the whole truth. You can try this with an old fashioned bike that has fork with a little angle there in between -- turn the handlebar 180 degrees and try driving that bike. I bet you a beer that you will be eating grass in a minute (try it on grass and not on paved road for the sake of your health).

What I'm trying to say is that when bike moves, there are other forces in to action than just the precession. One main thing is the dragging force of the front wheel and the line of action compared to the point around which the wheel actually turns. And the point around which the wheel actually tries to turn is not really where the wheel touches the ground but the line of steering axel. This is easy to understand and see if you lift the front into the air -- steering axel is the rigid part attached to the frame around which the whole moving part of front tries to revolve around.

So loosely speaking the momentum that will try to turn the wheel back to center line after displacement and around the steering axle is dependent on the distance of between the two points - the trail. At the extreme if trail would be negative it would mean that the whole set up is labile. Much like balancing pencil on your finger tip in upright position compared to keeping it in the same position by hanging it from the upper end. But this is not exact explanation and I'm not going to do the math. Not at least right now but maybe some day.

White walls

Something I felt I must have, are white wall tyres. These arrived to my office today and I just unpacked them second ago to see how they really look like. They seem to be about the right size I guess and pretty as a little piggy.

Back in the garage

Not so long summer is slowly over. This weekend we did a little tour but it may well be the last for this season. It sounds sad but at the same time I'm thrilled because I can dive back into the Shovel project.

What have I done during the summer to advance it? Lots and lots of thinking but not saving money for the parts - shame on me. I wanted to go surfing and to Norway so there went my money. Though it was the plan from the day one since I promised to my wife that the project will not take ALL our money, while it probably will take the most. Building a bike is not that cheap, not in Finland anyway because with the price of the useless frame and the few boxes of parts I could have bought a car that would still run. Didn't need the car did I? But that is my excuse for some things pending - priorities.

Anyway, I said I've been thinking. And the thing I've been thinking about is what kind of bike I want to go for in bit more details. It is soon time for the first decisions which will be about the wheels. I will need to re-use the hubs from the old wheels and what I need to buy are the hoops and spokes. Smart move would be to leave assembling of the wheels to the professionals but similarly it would be way smarter to just to buy a damn bike than trying to make one. So you bet I will be trying myself.

Why are the wheels the first thing to decide and why is it so important? It is because deciding the size of the wheels and putting them as far apart as I intend to (determining the wheelbase) will dictate how the frame needs to be built. So there we go, get the wheels or at least make up your mind. Draw the frame, calculate the right angles, buy big pile of beer and as friends to make a frame jig. Then starts cutting the frame in parts and welding it into new shape.

I'm telling these things as if you would know nothing about bikes. I don't intend to write this to anyone with experience -- what sense that would make for anyone with knowhow to read this. Except for the entertainment of seeing a newbie struggle and learn. If you that's your reason, I'm totally fine with it.

I mentioned some mysterious angles and I'll dive into them in the next post.

Mirror mirror -- you are worth nothing

Oh, I forgot to tell. I installed the mirrors from the project bike to my riding one for the summer. They look pretty but are useless because I can't adjust them so that I would actually see something. Maybe if I flip them upside down or something.

Summer is for riding

Summer in Finland is short and the winter is long. So the winter is time for building and summer is for riding. Also, I have been saving money for the parts and drawing sketches of the frame. More about this at some point but now for something different.

Different bike shows are, of course, good places to meet people, to get ideas and to have some fun.

It has been a damn rainy summer (yeah california, the opposite of what you have), but we have made one trip to Sweden and one to Joutsa. Both happenings were bikes, beer and tent on a field type of scenarios. It's truly amazing what some people can build - it is inspiring in a way but also it makes one wonder about his own skills (or the lack thereof) - but to live is to learn, or to ride or what ever makes you smile and wanting for more. 

Mirror mirror

For the two past couple of visits to our garage I've been working with the riding bike and not the project. The reason is that snow is gone and sun has been shining. Thought right now it's below zero (Celsius, I'm european if you didn't guess - but I'm sure you did) and there might be some more snow to be coming but I want to be ready when the time is right. Anyway, soon I should be getting back to writing about the project again.

The handlebar is on it's place and the electric wiring from controls now runs inside the bar. I did cut all the wires to be able to get them inside and I still have to re-connect them all. The new handlebar is not much higher nor wider than the old one, but now that the wiring runs inside the distance from controls grew longer. It means, that I'll have to see if I can just tin the wires back together or do I need extend them all. Then the only thing left is to hope and check that everything still works.

There was yet another subplot to the story. Since I for sure wont be needing the mirrors for the shovel quite yet I decided to borrow them to the sport. I can return them then after a year or probably two when I might have shovel on the road. These vintage pieces just look much nicer than Sports original ones. But as you can guess, nothing ever works without a little effort. I had to re-do the mounting bolts holding the mirrors because the ones from Shovel were too short for the Sport. But nothing major and it went well while sipping some beer - after all it was a Saturday evening.

Spring is coming

There is not much happening with the project. Frame is stripped and the transmission is still unopened. Though I drained the oil from it to find there was no oil. I'm changing the handlebar to my other bike mostly because there happened to be one extra lying about. Have to drill holes so I can pull the wiring inside. Not that I actually wanted to hide them but it's a structural necessity.

And the bike itself 

But surely there always needs to be a pic about the project no matter how unrelated so here 

And here 

The frame

The frame doesn't look all that rigid. But it's hardly a problem. Otherwise it's close to the time to start to figure out what to do to the frame. Hardtail - probably not but the tail looks bit weird so something needs to be done. Maybe I'll try to dry fit the engine and gas tank and maybe saddle to help envisioning what it could become.

Wrote the text above the pic couple of days ago and now I'm adding this. The more I spend time staring at the frame and looking bike pics on the internet, the more convinced I become that it has to be turned into a hard tail. I wasn't especially for it for couple of reasons, one small being that have so nice looking vintage pair if suspension to go with it. But there is no denying that it'll probably just look so much better as hard tail. There seems to be no obvious way of having suspension there that would look as nice as I'd like to. But I'll reserve a right to change my mind as many times as I want to; especially if I can come up with an installation that would both work and look awesome. 

My gas tank arrived

The person who sold me the project runs a actual bike repair shop. He said that the bike I bought, originally came with a gas tank, but it had some special painting on it and he therefore took the tank to a display at the shop. Too bad I don't have a picture of it and I haven't seen the original tank myself. But hopefully I can visit the shop and take a pic just to have it. Anyway, I got a new tank. I'm going to skip some details here but I had to make a quick decision on what kind of tank I wanted and just said that I wanted a wide one, because that much I knew. And it feels like a right bet.

Well there it is then. It feels almost too easy to start with a clean, smooth tank like this since I've seen how much some people put effort into actually making a good tank out of something that looks like it was hit by a train. But let's not celebrate quite yet and remember how much experience I have on installing any sort of tank. So I'm sure there will be just enough work for me even if I don't have to fix the tank itself, because, let's face it; currently I don't have a clue what I'm supposed to do or how it's supposed to be sitting on the frame. But that is just temporary - eventually I will know.

The engine

Just realized I didn't have a pic of the engine yet. Well, that's pretty much it.

Skeletons in the closet

If I was building this for Jack Skellington it would be almost done. 

There it is

Got it out relatively smooth. Had to open one left handed bolt holding the wheel of the secondary drive. This because there was a chain guide so close to drive that I couldn't pull the chain off from the wheel. Could have broken the chain as well but I'm actually glad I opened the bolt because it was way easier than trying to do it now that the whole thing is not attached to anything.

Loosen the axle, loosen the thingy holding it in place and the chain came off. Have to break the chain at some point but didn't have to bother quite yet.

Removing start and gear

There she sits. Let's see if it comes off nice and easy.

Eagle fly free

Bird is the word - or at least it used to be somewhere in time. As a not American I think I see it in a very different way than maybe many of the US born or raised people do. I do know what it represents but it doesn't represent the same thing to me - to me it represents something foreign. And bikes.

 I don't remember seeing many of these logos in modern bikes but older bikes used to have plenty of these. I think I'll do some digging and let you know if I can find something about when they became popular and when they ceased to be the standard decoration.

Feeling it

It's not that hard to strip it to skeleton piece by piece. As always it's getting the djinn back into the bottle that's difficult. Next thing after taking the loose parts out is to dismantle the transmission. There is something weird about it. There is a washer between the two halves of the cover making sure that they don't fit right, why the hell? Probably it has been opened and the cover has just been put loosely back together but I still have on idea what's the point of the washer there in between.

Trying to picture what it could become

Friend here got an extra pair of these. The height seems right. It's definitely along the lines I had in mind. The oil tank was cool also so maybe I'm able to use many of the parts I didn't come to think I can recycle. Of course it's too early to tell - I just have to keep on going and I believe the plan will reveal itself.

I think I'm going to use this pretty thing.

All sorts of parts - there are actually plenty of parts I've no idea what they are supposed to be doing. But more about that when I get to the engine and the clutch.

...and here.

Here it is...

I've had a bike that I bought as a new for some years. I really haven't done modifications to it and I have no experience in building bikes at all. But it just so happened, that yesterday I bought couple of boxes full of parts and a rolling frame. Together, what is in the boxes and the frame should make up -73 shovelhead.

I've no idea what I'm doing here but exactly for that reason I decided to share the story. I'm expecting some embarrassing wtf moments but hoping for end where I can ride to sunset with a bike that looks like me.